Phenolic resins have heretofore been used in a variety of fields such as various molding compounds, adhesives, coatings, plywood, and laminates but their drawback common to these uses is brittleness.
It is known that polymers having terminal functional groups, when used in combination with suitable curing agents, give cured products displaying good rubber-like elasticity. The main chains of such known polymers having terminal functional groups include polyether polymers such as polyethylene oxide; hydrocarbon polymers such as polyisobutylene, polybutadiene, polyisoprene and polychloroprene, inclusive of hydrogenation products thereof; and polyester polymers such as polyethylene terephthalate, polybutylene terephthalate, polycaprolactone, etc. and according td the backbone structure and mode of crosslinking, these polymers find application in a variety of uses of their own. However, most of them are polymers produced by ionic polymerization or polycondensation, and few vinyl polymers having functional groups at molecular termini, particularly vinyl polymers having phenol groups as a functional group, are available for commercial use.
In the above state of the art, the present invention has for its object to provide a phenolic-resin-based thermocurable composition giving cured products having flexibility.